The Distribution of Abscisic Acid in Pisum sativum Plants during Seed Development

Abstract

The ABA contents of a range of tissues of Pisum sativum L. were determined throughout the period of seed development using an ELISA. The absolute amount of ABA in embryos increased in parallel with seed fresh weight, while the amount in seed coats decreased. When expressed as a function of fresh weight the ABA content of the embryo was high throughout seed development, while the level in the seed coats decreased. The levels of ABA in other tissues were lower and did not parallel changes in the seeds. A study of the distribution of ABA in a complete plant revealed that over 90 % of the ABA in the plant was located in the seeds. Although the experiments do not provide direct evidence of the source of ABA in the seed, the results do suggest that synthesis and metabolism of ABA in the seeds is largely independent of ABA levels in the vegetative tissues.